The purpose of this research project is to examine in detail the possibility that subtle midfrequency hearing dysfunction that goes undetected by standard pure-tone audiometry may exist in noise-exposed listeners. There is sufficient evidence to support this possibility available from: (1) correlations between cochlear histology and pure-tone thresholds; (2) studies of TTS in man; and (3) preliminary studies of subtle midfrequency dysfunction in noise-exposed persons. In addition, recent data imply that the presence of undetected midfrequency pathology may explain some of the difficulty that noise-exposed listeners have in understanding speech, especially in noisy environments. The present project is designed to evaluate midfrequency auditory function in a reasonably large sample of noise-exposed listeners (N equals 20-25) and to examine the relationship between the extent of dysfunction and communicative breakdown. Measures used in this study to assess midfrequency dysfunction include: (1) psychophysical tuning curves; (2) pure-tone masking patterns; (3) two-tone unmasking; and (4) masked speech reception threshold. In addition, communication breakdown is assessed with the California Consonant Test.